1. FIELD OF THE INVENTION
This invention relates generally to composite photography and pertains more particularly to a polarizing beam splitting unit employed therein to prevent degradation of the composite image.
2. DESCRIPTION OF THE PRIOR ART
The front projection technique of making composite photographs is well known. Equally well known are the problems attending such a technique. Since the background image is projected onto a screen, a high intensity reflection from the screen is desired. However, in order to properly illuminate a subject standing in front of the screen, fill light is utilized. If the source of fill light is well to one side, the amount of unwanted fill light impinging on the screen can be minimized. However, when this approach is taken, the advantage of the fill light is substantially reduced, attributable largely to the failure to eliminate the shadows that the subject casts. Actually, the placing of the fill light source or sources too far to one side is apt to produce even more pronounced shadows.
Generally, the presence of flare light acts to wash out the contrast of the composite image, much like attempting to project a color slide in a lighted room. The prior art has recognized that there are two major sources of flare light. The first one is from the projector that is utilized to provide the background image. More specifically, some of the light from the projector (that which is not reflected onto the screen) passes through the beam splitter and various efforts have been made to trap this unwanted illumination so that it does not reach the camera and thereby adversely affect the composite photograph. A second major source of flare light arises because the conventional lighting used to illuminate the subject must of necessity be relatively high as far as its intensity is concerned and if this light falls on the projection screen, the projected image is washed out in proportion to the amount striking the screen.
Consequently, the fill lighting units used to illuminate the subject have heretofore been placed well off to one side. The offsetting of the subject lighting units, however, prevents the use of the normal amount of fill light that is conventionally required to prevent the casting of harsh shadows which appear in the composite photograph. Also, attempts have been made to employ screening means to block the unwanted fill light from reaching the projecting screen directly. This has not proved to be effective, and becomes quite costly.